This is generally known as the ApoE4 allele of ApoE and is associated with increased risk of Alzheimer's. 20-25% of individuals are heterozygous for this variant, and 1-2% are homozygous. Data from Khachaturian et al. suggests an average 7% of all individuals developed Alzheimer's by the age of 80; when this is split by ApoE4 status: 10% of ApoE4 heterozygotes (3% increased attributable risk), 40% of ApoE4 homozygotes (33% increased attributable risk), and 5% of non-carriers (2% decreased attributable risk). Notably, their model suggests 70-75% of people would eventually develop Alzheimer's by the age of 100 regardless of ApoE4 genotype (and 25-30% are resistant, regardless of genotype), but that ApoE4 variants shift the disease onset to occur significantly earlier (4 years earlier for heterozygous carriers, 13 years for homozygotes).

This variant (also called C3F) is common in Europeans (10.2% allele frequency), and is associated with age-related macular degeneration. In the US, 1.5% of adults over 40 have the disease, but the incidence increases strongly with age (>15% in women over 80). Assuming an average lifetime risk of ~10%, heterozygous individuals have a ~13% risk and homozygous have ~20%.

This common noncoding genetic variant has an allele frequency of ~30% and is associated with an increased risk of hypertension. If ~25% of non-carriers have hypertension, Bonnardeaux et al's data predict ~4% increased risk of hypertension per copy of this variant. This SNP is in the 3' noncoding region of the AGTR1 transcript (angiotensin II type 1 receptor), also known as AT2R1 or AT1R, which is a target of hypertension drugs.

Causes Adenosine Deaminase Deficiency in a recessive manner. Most of the time individuals do not report symptoms, but when symptoms do exist they to be post-exercise symptoms of muscle weakness, muscle pain, and getting tired more quickly.

This variant is associated with a slightly increased risk of tuberculosis. It is unclear whether it is itself causal, or in linkage disequilibrium with some other causal variant that has a stronger effect.

This is a common variant was first reported as a polymorphism. It has since had mixed associations with cancer: Storey et al. conclude a 7x *increased* risk of HPV cancer for homozygotes vs hets, but Jones et al. find a 1.98x *decreased* risk for colorectal cancer. This variant may have significant impact on particular cancers, but it is unclear what effect it has on the overall burden of cancer.

A single sporadic observation implicated this variant in causing myeloperoxidase (MPO) deficiency in a recessive manner, but lacks any statistical significance. MPO deficiency generally causes no symptoms, but there are reports of associations with some cancers.

Alone, this variant is known as TPMT*3C -- but often, especially in Caucasians, it is found together with another nonsynonymous variant (A154T) to produce the TPMT*3A variant. Both variants are associated with loss of thiopurine methyltransferase (TPMT) activity, although *3C is milder than *3A. Inability to metabolize thiopurine drugs can lead to severe adverse reactions. Heterozygotes may be advised to take a reduced dosage due to reduced metabolism of the drug.

Usually this variant is found in combination Y240C, forming the TPMT*3A variant. When alone, this variant produces the *3B variant. Both variants are associated with loss of thiopurine methyltransferase (TPMT) activity. Inability to metabolize thiopurine drugs can lead to severe adverse reactions. Heterozygotes may be advised to take a reduced dosage due to reduced metabolism of the drug.

This recessive protective variant confers resistance to norovirus (which causes stomach flu). 20% of Caucasians and Africans are homozygous for this variant and are "non-secretors": they do not express ABO blood type antigens in their saliva or mucosal surfaces. Most strains of norovirus bind to these antigens in the gut, and so this non-secretor status confers almost total resistantance to most types of norovirus. There are notable exceptions, some strains of norovirus bind a different target and are equally infectious for secretors and non-secretors.

This variant is associated with some protective effects for prion disease -- individuals homozygous for this variant are less susceptible to Creutzfeldt-Jakob, and Papua New Guinea individuals heterozygotes at this site are less susceptible to kuru.

Associated with a decreased risk for age related macular degeneration (ARMD). Homozygotes for this have a 4-5% decreased attributable risk (3-4% vs. average 8% risk), heterozygotes have slightly lower than average risk (7%). Non-carriers have an increased risk (12-13%). ARMD impairs sharp vision as age progresses. While there is no cure, treatment can slow progression of the disease and environmental factors (smoking and obesity) contribute to higher risk.

This variant is associated with decreased risk of type 2 diabetes. It is unclear whether this variant has additive effects, or acts in a dominant or recessive manner. Assuming diabetes has a lifetime risk of 36%, we estimate a decreased risk of around 1-2% per copy of this variant.

This common variant (HapMap 24.1% allele frequency) causes a loss of a glycosylation site (affecting the size of the protein when studied with gel electrophoresis) but does not affect enzyme activity or stability.

This variant has a 3.5% allele frequency in 1000 genomes data. Although OMIM links this to disease, the paper they reference uses in vitro data to conclude that this is a functionally neutral polymorphism.

One publication suggested that this variant possibly causes Leber's congenital amaurosis in a recessive manner, but the frequency data (36% in 1000 genomes) contradicts any significant pathogenic effect.

Associated with exfoliative glaucoma & syndrome (XFG & XFS) in various populations, but with contradicting results (protective in Caucasians, pathogenic in Japanese). Based on this it seems the variation itself -- although it affects protein structure -- is not itself causing disease. Instead it is likely associated with other nearby causal variants. As such, it is evaluated as benign by GET-Evidence (which focuses on reporting causal variants). See detailed variant report for disease risk associations.

Probably benign. This variant was implicated as causing Refsum Disease in a recessive manner, but a subsequent publication noted that all instances were linked with other explanatory mutations. The high allele frequency of this variant in the population (7-13%) contradicts a pathogenic hypothesis.

Probably benign. One report linked this variant to high triglycerides, but a later paper found a nearby SNP with similar association and suggests that both findings are caused by linkage to an undiscovered causal variant.

This variant is associated with "taster" status of PTC, along with 49P and 262A. Due to linkage disequilibrium, the independent effects of positions 296 and 262 is unclear. The presence of 49P confers taster status in a dominant fashion, but in the absence of 49P, the presence of 262A/296V is still positively associated with tasting PTC.